1. Field of the Invention
The invention relates to a system for processing an e-mail and method thereof, and more specifically, to a system for processing information including a mail subject of an e-mail not including all contents of the e-mail for controlling delivery of the mail subject requested by a host and method thereof.
2. Description of the Prior Art
Due to the volume of spam mail increasing on a daily basis, more and more network appliance vendors have proposed solutions for detecting spam mail. Briefly, there are two scenarios for analyzing spam mail.
Please refer to FIG. 1. FIG. 1 is a block diagram of a system 100 for detecting a spam mail according to the related art. The system 100 includes a host 110, a gateway 120 and a mail server 130. In a first scenario the mail server 130 stores a plurality of e-mails. The host 110 issues a mail request to get a desired e-mail. The gateway 120 is coupled to the host 110 and the first server 130 for transmitting the requested e-mail to the addressee (the host 110). Please note that the gateway 120 is an MTA (Mail Transport Agent) in the system 100. The MTA acts as a mail server of the host 110 for receiving the mail request issued from the host 110 and further serves as a mail client of the mail server 130 for issuing another mail request to the mail server 130 to get the e-mail requested by the host 110. The gateway 120 stores the whole mail on the network appliance storage and analyzes these mails utilizing a vendor's methodology (for example, a white list or a black list, fingerprint, IP address, DNS, etc.). This is the most popular implementation for a network appliance vendor.
Please refer to FIG. 1 again. In another scenario based on the system architecture shown in FIG. 1, the gateway 120 acts as a transparent mail parser on the network appliance. When the host 110 sends a spam mail to the mail server 130, the mail parser 120 analyzes this traffic and activates the anti-spam function directly. There will be no additional storage on the network appliance and this implementation is called a stream-based anti-spam methodology.
Normally, the stream-based anti-spam methodology is not used for supporting IMAP protocol because this protocol supports fetching a mail subject without any mail contents. On the other hand, the e-mail can be stored and shared on the mail server 130. The stream-based anti-spam methodology cannot analyze the e-mail by the mail subject only, so the network appliance will analyze the same e-mail many times because the e-mail is shared/stored on the mail server 130 and not moved to the host 110 that requested the e-mail.
Therefore, a new and novel system architecture is needed to provide a stream-based anti-spam system that supports the IMAP protocol.